Intelligent synchronous modem and communication system incorporating the same

ABSTRACT

An intelligent synchronous modem and data communication systems utilizing the intelligent synchronous modem are provided. The modem comprises: at least one connector having a first and a second port for primary and secondary channels of communication with a host computer, wherein the primary communication channel is for communication of synchronous data and the secondary communication channel is for communication of asynchronous data; a microprocessor for recognizing and executing commands of the host computer, wherein the commands are in the form of asynchronous data received over the secondary communication channel and interface means for interfacing the microprocessor with telephone lines, wherein synchronous data received by the microprocessor is sent to the interface means. 
     The data communication system of the invention comprises: a host computer including asynchronous and synchronous communication ports, wherein the host computer is arranged to send command mode data through the asynchronous port, and data mode data through the synchronous port; and intelligent synchronous modem as described above; at least one cable for connecting the synchronous port of the host computer with said synchronous port of the modem, and for connecting the asynchronous port of the host computer with the asynchronous port of the modem; and code/decode means for coding data received from the host computer into a synchronous format, and for decoding synchronous format data received from a second computer into data understandable by the host computer. 
     Preferably, the modem of the invention is arranged to permit the conversion of the modem from an intelligent synchronous modem into an intelligent asynchronous modem through the use of data path logic circuitry which is controlled by the microprocessor of the modem.

BACKGROUND

This invention relates generally to modems and communication systems forthe transmission of data over a switched network. More particularly,this invention relates to an intelligent synchronous modem and acommunication system incorporating an intelligent synchronous modemwhich will permit the interface of a microcomputer or personal computerwith a mainframe computer requiring synchronous communication.

Both synchronous modems and intelligent asynchronous modems are known inthe art. Typically, database services utilize mainframes whichcommunicate in an asynchronous mode. Thus, with an intelligentasynchronous modem, a user could insert a disk with communicationsoftware into his PC and start the program. The software, in commandmode, then instructs the modem to dial the telephone number keyed in bythe user with the command: ATD (xxx) xxx-xxxx; where "AT" means"attention", and "D" means "dial the following number". The modem willthen dial the given number and interrupt the PC with the message"CONNECT" when the connection with the remote computer has beenaccomplished. The modem will then leave its "command mode" and enter its"data mode". Once in the data mode, the modem simply acts as amodulator/demodulator for whatever information is being transmittedbetween the computers. After data transmission is completed, thecomputer will then use command mode to instruct the modem to "hang up".Because the modem can understand when it is being commanded to enter thecommand and data modes, it is called an "intelligent" modem. Thoseskilled in the art will understand that the nature of asynchronouscommunication permits the implementation of such an intelligent modem,as asynchronous data is sent at whatever rate it is received, and it isnot enveloped with excess information which must be stripped tounderstand the data. Thus, the appearance of particular controllanguage, in any location and at any time in the data stream, will causethe intelligent modem to enter or leave command mode.

Often, in large corporations, computer systems are arranged forsynchronous communication, and synchronous modems have long beenavailable to facilitate transmission of synchronous messages.Synchronous data is sent according to a particular protocol andaccording to a clock. Because a protocol is used, a PC must be arrangedto talk according to that protocol. Typically, a "SYNC card" is used togenerate the proper protocol and thus translate the information beingoutput by the PC into properly formatted information. The informationmay then be sent via the modem to the mainframe computer. The modem'sfunction in such an arrangement is simply to convert each bit ofinformation into phone line compatible information. Because theinformation is being sent according to a complex protocol, the modem(without the use of expensive and sophisticated hardware) is incapableof determining whether any of the information is meant for it ratherthan the distant computer. Thus, the synchronous modems of the art arenon-intelligent. They act in "data mode" only and simply pump theinformation through the line. Typically, all "command mode" informationis accomplished manually such that operators place the calls to themainframe and manually transfer the line to the modem of the PC.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide an intelligentsynchronous modem.

It is a further object of the invention to provide a communicationsystem having an intelligent synchronous modem as a component.

In accordance with the objects of the present invention, an intelligentsynchronous modem is provided and broadly comprises:

(a) at least one connector having a primary and a secondary port forprimary and secondary channels of communication with a host computer,wherein the primary communication channel is for communication ofsynchronous data and the secondary communication channel is forcommunication of asynchronous data;

(b) a microprocessor for receiving, recognizing, and executing commandsof said host computer, wherein said commands are in the form ofasynchronous command data received over said secondary communicationchannel; and

(c) interface means for interfacing said microprocessor with telephonelines, wherein synchronous data mode data received by saidmicroprocessor from said host computer is sent to said interface means.

Preferably, the intelligent synchronous modem further comprisesscrambling means for scrambling synchronous data into a proper formatfor transmittal to a remote computer via telephone lines, and forunscrambling data coming into the scrambling means from a remotecomputer. Also, preferably, the microprocessor of the intelligentsynchronous modem is arranged to modulate the synchronous data receivedfor output to a remote computer, and typically outputs that modulateddata in an eight-bit parallel format. The interface means of the modemis arranged to convert the parallel data received from saidmicroprocessor into serial format, to convert digital information intoanalog information for transmission over the telephone lines, to convertincoming analog information into digital information, and to filterfrequencies so as to separate transmit and receive signals. Further, themodem of the invention is preferably arranged to permit the conversionof the modem from an intelligent synchronous modem into an intelligentasynchronous modem through the use of data path logic circuitry which iscontrolled by the microprocessor of the modem.

According to another aspect of the invention, a data communicationsystem is provided and comprises:

(a) a host computer including asynchronous and synchronous communicationports, wherein said computer is arranged to send command mode datathrough said asynchronous port, and data mode data through saidsynchronous port;

(b) an intelligent synchronous modem, including

first and second ports for primary and secondary channels forcommunication with said host computer, wherein the primary communicationchannel is for communication of data mode data and the secondarycommunication channel is for communication of command data,

a microprocessor for receiving, recognizing, and executing commands ofsaid host computer, wherein said commands are in the form ofasynchronous command data received over said secondary communicationchannel, and

interface means for interfacing said microprocessor with telephonelines;

(c) at least one cable for connecting said synchronous port of said hostcomputer with said synchronous port of said modem, and for connectingsaid asynchronous port of said host computer with said asynchronous portof said modem; and

(d) code/decode means for coding raw data of said host computer into asynchronous protocol, and for decoding synchronous protocol datareceived from a remote computer into data understandable by said hostcomputer.

A better understanding of the invention, and additional advantages andobjects of the invention will become apparent to those skilled in theart upon reference to the detailed description and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the data communication system of theinvention.

FIG. 2 is a data flow chart of the intelligent synchronous modem of theinvention.

FIG. 3 is a flow chart of the software logic controlling the datacommunication system invention of FIG. 1.

FIG. 4 is an alternative embodiment of the data communication system ofthe invention.

DETAILED DESCRIPTION

Turning to FIG. 1, the data communication system 10 of the inventiongenerally comprises a host computer 15, an intelligent synchronous modem20, and a cable 22 connecting the modem 20 to the host computer 15. Thehost computer 15 is typically a personal computer or the like, which isarranged to have a connector 24 for an asynchronous port, and a secondconnector 26 for a synchronous port. The computer 15 is further arrangedto send (and receive) asynchronous data from the asynchronous port, andsynchronous data from the synchronous port. When the system is in itsintelligent synchronous mode, the asynchronous data sent from theasynchronous port is "command mode" data intended for use by the modemitself, while the synchronous data sent from the synchronous port is"data mode" data intended for communication with a second or remote(mainframe) computer.

The intelligent synchronous modem 20 of the system invention has aconnector 28 which includes a first port for a primary communicationchannel for communication of synchronous data, and a second port for asecondary communication channel for communication of command data. Theport of the primary channel preferably consists of the standardconfiguration of connector pins used on most modems of the art. The portof the secondary channel preferably consists of the secondary pins ofthe RS232 connector which are known as the secondary RS232 EIA signals.The modem 20 also includes a microprocessor for receiving, recognizing,and executing the asynchronous data commands of the host computer, andan interface means for interfacing the microprocessor with telephonelines. A more complete description of the components and working of themodem 20 will be had hereinafter with reference to FIG. 2.

The primary and secondary communication channels for the transfer ofsynchronous and asynchronous data are contained in "Y" -cable 22 whichconnects connectors 24 and 26 of the host computer 15 with connector 28of modem 20. It should be appreciated that two (or more) cables could beused to house the primary and secondary channels, provided properconnectors are provided. Moroever, as will be described hereinafter withreference to FIG. 4, if a host computer having a single connectorhousing two ports was provided, a single standard cable could be used.However, with the standard computer arrangements presently available,the Y-cable offers the advantages of requiring only a single cable, andnegating the extra cost of additional connectors on the modem end.

Finally, with reference to the components of the data communicationsystem 10 of the invention, system 10 requires a coding/decoding meansfor coding raw data of the host computer into a synchronous protocol fortransfer through the microprocessor of the modem 20 to the interfacemeans of the modem 20, and for decoding synchronous protocol datareceived from a remote computer into data understandable by said hostcomputer. Those skilled in the art will recognize that the requiredcoding/decoding means is preferably a part of the host computer 15itself or a stand alone component. "Sync Cards" for computers, which areknown in the art, are typically suitable as code/decode means. The SyncCards of the art take the data or code of a personal computer and codesit into the required protocol such as HDLC/SDLC or BISYNC. Thecode/decode means thus acts to take raw data of the host computer 15,and translate them into a complex protocol which is understood by aremote mainframe.

Turning to FIG. 2, the data path and the components of the intelligentsynchronous modem 20 of the invention is seen. To function effectively,the modem 20 need only include a single connector 28 housing ports 30and 32 for receiving a primary communication channel and a secondarycommunication channel respectively. The primary communication channel ispreferably designated for the communication of synchronous data, whilethe secondary channel is designated for the communication ofasynchronous data with the host computer 15. The intelligent synchronousmodem invention 20 further includes a microprocessor 35 for receiving,recognizing, and executing commands of the host computer, wherein thecommands are in the form of asynchronous data received via the secondarycommunication channel, and interface means 36 for interfacing themicroprocessor 35 with telephone lines 50, wherein synchronous datareceived by the microprocessor 35 is passed through to the interfacemeans 36. Also, as will be described hereinafter in detail, the modem 20preferably further comprises scrambling means 38 as is known in the artfor scrambling synchronous data into a proper format for transmittal toand receipt by a remote computer via telephone lines 50, and forunscrambling data coming into the scrambling means 38 from a remotecomputer. Finally, data path logic circuitry 40, comprising switches andgates 42, 44, 45, 46, and 48 is preferably provided to permit theconversion of the modem 20 from an intelligent synchronous modem into anintelligent asynchronous modem.

As aforementioned, the modem invention 20 includes a connector 28, suchas an RS232 connector for receiving primary and secondary datacommunication channels. The connector 28 can be thought of as having twoports 30 and 32, each port connecting to a receive line and a transmitline in the Y cable. Thus, data entering the modem 20 from the hostcomputer 15 enters on the transmit line, and data being sent to the hostcomputer 15 from the modem 20 leaves on the receive line. Those skilledin the art will appreciate that the naming of the transmit and receivelines according to the direction of data flow is governed by convention.

In the intelligent synchronous modem 20, a primary channel is designatedto receive and transmit synchronous data. The synchronous data receivedand transmitted is "data mode" data, and does not include any "commandmode" data. A secondary channel likewise is designated to receive andtransmit asynchronous data, which includes only "command mode" data andno "data mode" data. Again, those skilled in the art will appreciatethat the terminology "primary" and "secondary" channels is one ofconvenience, and that, if desired the type of information received oneach may be reversed. Nevertheless, it should be appreciated thatcommands are received by the modem 20 via the asynchronous channel, anddata for transmittal to the mainframe is received by the modem via thesynchronous channel.

Turning to FIG. 3 in conjunction with FIG. 2, a flow chart is providedof the software controlling computer 15 which permits a user of the hostcomputer 15 to communicate with a mainframe computer via modem 20.Typically, having previously set the connector and cable arrangements asprovided by FIG. 1, a user would load asynchronous communicationsoftware into the memory of host computer 15 and execute the program at52. Then, by issuing asynchronous command strings to the microprocessor35 of the modem 20 via the secondary channel (which is always connectedto the microprocessor), the user of computer 15 would initialize themodem parameters at 54 (i.e. direct the setting of switches 42, 44, 45,and 46, and the second input 47 into AND gate 48), to prepare for asynchronous connection. A synchronous software package could then beloaded at 56 into a predetermined location in the computer memory, suchthat it is co-resident in memory with the asynchronous software package.The computer 15 and modem 20 will then be set to make contact with asecond (mainframe) computer.

At 58, the user of computer 15 should issue an asynchronous "dialcommand" to the modem 20 via the secondary channel. The command string,which directs the modem to contact a computer using synchronousprotocol, proceeds through the transmit line of port 32 and throughswitch 42 to the universal asynchronous receiver transmitter (UART)section of microprocessor 35. According to the preferred embodiment, aneight-bit microprocessor such as an Intel 8051 will suffice for theapplications used herein, although depending on the applicationsdifferent microprocessors of different capacities could be used.Because, in the intelligent synchronous modem mode, switch 44 is closedin the direction of the primary channel, it is open in the direction ofthe secondary channel. Hence, the dial command string (or anyasynchronous command string) is not sent to scrambler 38 for delivery tothe phone lines.

Upon receiving the "dial" command, the microprocessor 35 performsdifferent functions as are well known in the art to establish contactwith the synchronous mainframe computer. Upon establishing contact, themicroprocessor 35 of modem 20 sends an asynchronous signal to computer15 via switch 45 and the receive line of port 32 to inform computer 15of the contact. After receiving a signal that contact has been made,computer 15 sets and holds the RS232 interface signals at 62 as requiredto maintain a synchronous connection. Then, either automatically, or bythe request of the user, the synchronous software is addressed at 64,and executed at 66 such that any data leaving computer 15 thereafterwill be sent via the primary channel. This switch-over from theasynchronous to the synchronous software package may require the use ofinterrupt handling techniques known in the art. Thus, at 68, the hostcomputer 15 and mainframe computer are in contact, and data transfersmay be had in a synchronous fashion.

In order to permit a meaningful transfer of information, switch logic 40must be properly set by the modem microprocessor 35 to connect the modemmicroprocessor 35, the scrambling means 38, and the synchronous port 30.Thus, synchronous information being sent by the host computer 15 isreceived at the synchronous port 30 of connector 28. The information ordata is sent through switch 44 to the scrambling means 38 where clockinformation and the synchronous data which is in its proper protocol aremerged. The scrambled data is then sent via the TD (transmit data)output of means 38 to the microprocessor 35. Provided the handshakingand other status information being received by the microprocessor 35from scrambling means 38 (via transmit data out (TX out) and serialreceive data (SRD)) is proper, the microprocessor 35 modulates thesignal so that it may be properly sent over telephone wires 50. Themicroprocessor then forwards the information to interface means 36.Interface means 36 serves to convert the digital information receivedfrom the microprocessor 35 into analog signals for transmission overtelephone wires 50. Interface means 36 further serves as a frequencyfilter to separate signals which are being transmitted from signalswhich are being received. Moreover, because the microprocessor typicallyis arranged to output information in a parallel format, the interfacemeans 36 can be arranged to convert parallel information received fromthe microprocessor into serial format.

Information being sent from the remote mainframe computer over telephonelines 50 to host computer 15 is also received by telephone lineinterface means 36 which converts the analog information into digitaldata. The digital data is then demodulated by a digital signal processor51 such as the 7720 DSP chip of the NEC Corporation of Massachusetts,and sent to scrambler 38 which descrambles the synchronous data. Thesynchronous data are sent via port BB of means 38 through switch 46, ANDgate 48, and port 30 of connector 28, to computer 15 via the primarychannel. Because switch 45 is open to the information leaving decoder38, no synchronous information is transmitted over the secondarychannel.

It will be appreciated that the data path logic circuitry is controlledby microprocessor 35. Switch 46 is used to select the receiver (whichmatches the baud rate) for the incoming information. AND gate 48 is usedin the intelligent synchronous modem mode to block incoming data if itis determined that the quality of the incoming information is subpar orthe like. The microprocessor 35 controls the setting of the second inputinto AND gate 48, and uses information leaving the digital signalprocessor 51 to make such a determination.

After the communication session consisting of transferring data betweenhost computer 15 and a mainframe is completed, computer 15 may bedirected at 72 to exit the synchronous software package and return tothe asynchronous package resident in memory. This direction can eithertake the form of a direct command from the user, or a command appendedto the end of the synchronous software package or other automatic means.Thus, if no further data is being transmitted, the software might directitself to the address of the asynchronous package. Or, if a masterprogram or shell is utilized, the asynchronous package and synchronouspackages may be called and swapped in and out as required. Regardless,the computer 15 would return at 74 to the situation existant at 52 whereany additional communication to other computers would require additionalinitialization, etc.

Those skilled in the art should appreciate that the arrangement of modem20 of the invention as shown in FIG. 2 permits the conversion of themodem from an intelligent synchronous modem into an intelligentasynchronous modem through the use of data path logic circuitry. Thus,if desired, the parameters of modem 20 may be switched into theasynchronous mode by using only the secondary channel, by setting theinput 47 into AND gate 48 low, by closing switch 44 in the direction ofport 32, and by having switch 45 switch depending on whether data iscoming from microprocessor 35 or from decoder 38. Of course, if"Y"-cable 22 is replaced by an ordinary cable which is attached to theasynchronous port and connector of host computer 15, the primary channelmay be used and the switches set accordingly to provide the intelligentasynchronous modem.

In the intelligent asynchronous modem mode (using the Y-cable), theasynchronous software is loaded into memory and executed. With theparameters properly set, the host computer 15, by direction of the user,issues an asynchronous command string to dial a remote computer systemthat utilizes asynchronous communication. The command string is receivedat port 32, and with switches 42 and 44 closed in the direction toreceive the command string, the command is sent to both themicroprocessor 35 and the scrambler 38. Because the microprocessor 35can decipher the simple asynchronous command string, it enters itscommand mode and ignores the data being forwarded to it from the TXoutport of the scrambler 38. Instead, it follows the directions of thecommand string to dial a number and establish contact with anasynchronous computer. When contact is made, the microprocessor 35forwards a command mode message to the host computer 15 via switch 45and port 32 of connector 28.

When the user desires to send data to the second computer, the userdirects the host computer 15 to send a command mode message to themicroprocessor 35 to enter the "data mode". Data sent thereafter isstill received by both the microprocessor 35 and the scrambler 38.However, instead of ignoring the data being sent by the scrambler 38,the microprocessor 35 modulates the information and sends it to thetelephone line interface 36 for parallel to serial and digital to analogconversion. It should be appreciated that in the asynchronous mode, thescrambler 38 is arranged not only to scramble the data received from thehost computer 15, but to take the asynchronous data and convert it intoclocked data which can be transmitted over phone lines 50. The scrambler38 is informed of which mode it is operating in by an information bitfrom the microprocessor 35. It should also be appreciated that, in theasynchronous mode, the microprocessor 35 continues to monitor the databeing sent from the host computer 15. Thus, when the microprocessor isproperly signalled, it can reenter the command mode and stop the datatransmission.

Data being received from a remote computer in the intelligentasynchronous mode is received via telephone lines 50 at the interfacemeans 36 where it is filtered and undergoes and A/D conversion. The dataare then sent through demodulator 51 to scrambler 38 which unscramblesthe incoming clocked data and strips the clocking information from it.The unscrambled asynchronous signal is then sent to host computer 15 viaswitch 46, switch 45, and port 32. As aforementioned, in theasynchronous mode utilizing the "Y"-cable 22, the controllable input 47to AND gate 48 is set low by the microprocessor 35 such that noinformation may pass through the primary channel. Thus, in order forinformation to pass through the secondary channel, switch 45 must beclosed by microprocessor 35 in the direction permitting data to flowfrom the decoder 38 to port 32. Thus, switch 45 switches its position inthe asynchronous mode depending on the direction data is flowing. If, atany time, information simultaneously appears at switch 45 from both themicroprocessor 35 and the decoder 38, the switch preferably closes topermit the microprocessor information to flow. Also, if at any time, the"Y"-cable 22 is replaced by a standard cable, the microprocessor 35 ofthe modem will sense the change and redirect the switching network 40 sothat the primary channel can be used by the intelligent asynchronousmodem.

The modem 20 of the invention, if required, may also act in a "dumb"asynchronous or "dumb" synchronous mode. In both cases, only a singlecable is used rather than the Y-cable of the invention, and the hostcomputer 15 is connected to the modem 20 by the primary channel. Switch45 is opened completely so that no data may flow through, and switches42 and 44 are closed in the direction of the transmit line of port 30 sothat data may flow from the host computer 15 to both the microprocessor35 and scrambler 38.

Turning to FIG. 4, an alternative embodiment of the data communicationsystem of the invention is seen. The alternative data communicationsystem 110 of the invention generally comprises a host computer 115, anintelligent synchronous modem 120, and a standard cable 122 connectingthe modem 120 to the host computer 115. The host computer 115 istypically a personal computer or the like, which is arranged to have asingle connector 125. Thus, it will be recogized that the Sync and AsyncCards of the art are combined into a single card handling bothfunctions. For purposes of understanding, the asynchronous andsynchronous ports of the computer 115 can be thought of as being locatedin a position more internal to the computer than connector 125. Thus,the computer 115 sends and receives asynchronous data from anasynchronous port and synchronous data from a synchronous port byfunneling the data into the primary pins of connector 125. In additionto the primary pins, the SEC RTS pin 19 is used to provide informationas to whether the data being supplied is coming from the asynchronousport of computer 115 or the synchronous port. The data, including thepin 19 information are then sent to modem 120 over cable 122.

The intelligent synchronous modem 120 of the system invention 110 alsohas a single connector 128. Again, for purposes of understanding, thesynchronous and asynchronous ports of the modem 120 can be thought of asbeing more internal to the modem 120 than the connector 128. When datais sent by computer 115 to modem 120, the connector 128 of the modem 120acts as a switch to channel the data to the synchronous port or to theasynchronous port depending on the information received regarding pin19. Thus, in effect, the SEC RTS pin 19 is used as a control mechanismto multiplex asynchronous control data and synchronous data mode dataover the primary RS232 channel, where the asynchronous data sent fromthe asynchronous port is "command mode" data intended for use by themodem itself, while the synchronous data sent from the synchronous portis "data mode" data intended for communication with a remote computer.

As with the modem 20 of the system invention 10, modem 120 of system 110also includes a microprocessor for receiving, recognizing, and executingthe asynchronous data commands of the host computer and performing otherfunctions as described above with regard to the description ofmicroprocessor 35 of system 10, and an interface means for interfacingthe microprocessor with telephone lines and performing the functions asdescribed above with regard to interface means 36 of the system 10. Themodem 120 also preferably includes a scramler, switch logic, and adigital signal processor, which all perform the functions describedabove with regard to the description of similar components of modem 20of system invention 10.

Those skilled in the art will appreciate that the communication system110 utilizing the intelligent synchronous modem 120, can also be used tocommunicate in an intelligent asynchronous environment. Thus, pin 19 ofconnector 125 can either be fixed to indicate the flow of asynchronousinformation, or pin 19 information need not be sent to modem 120 at all.Regardless, the microprocessor of the modem 120 is used to set all theswitches of the modem as in the embodiment of system 10 and modem 20where a single cable and the primary channel are used.

Those skilled in the art will also appreciate that the communicationsystem 110, while described above for purposes of understanding as onlyusing a single (primary) communication channel, may also be thought ofas having both primary and secondary channels. The "primary" channel isfrom the synchronous port of Sync/Async Card of computer 115, to theprimary pins of connector 125, through cable 122, to the primary pins ofconnector 128, and to the synchronous port of the modem 120. The"secondary" channel would be from the asynchronous port of theSync/Async Card of computer 115, to the primary pins of connector 125,through cable 122, to the primary pins of connector 128, and to theasynchronous port of the modem 120. Thus, while data is passing onlyfrom the primary pins of one connector to the primary pins of a secondconnector, through a single cable, both a "primary" and "secondary"channel of communication exist. Moroever, if desired, both theasynchronous and synchronous ports of both modem 120 and computer 115may be thought of as being located in connectors 128 and 125respectively, as the exact "location" of a port is nebulous andunimportant. Thus, it will be appreciated that the alternativeembodiment 110 of the system invention is simply an equivalent of systeminvention 10.

There has been described and illustrated herein an intelligentsynchronous modem and communication systems incorporating such anintelligent synchronous modem. While particular embodiments of theinvention have been described, it is not intended that the invention belimited thereby, as it is intended that the invention be broad in scopeand that the specifications be read likewise. Thus, those skilled in theart will appreciate that a plethora of changes could be made to thedetails of the circuitry and the software without deviating from theinvention. For example, the data path "switches" of the invention can beimplemented in firmware, and/or as hardware. Likewise, the control ofthe user over the procedures and the parameters can range widely frompermitting or requiring a step-by-step intervention of the user to anautomatic procedure which has a minimum of user intervention.

It further will be understood that the different components of the modemcan be combined or split so that one chip could assume the functions ofothers, or so that many discrete components are used instead ofintegrated circuits. Moreover, while the computer was described ashaving either one or two connectors depending on the system embodiment,and the modem was described as having a single connector for bothembodiments, those skilled in the art will appreciate that it is amatter of choice whether to maintain separate Sync and Async Cards withtheir respective connectors on the computer end or to provide twoconnectors on the modem end, as any combination of the same could beaccommodated in both system embodiments. Likewise, depending on thenumber and location of connectors, the connection between the computerand the modem may range from a single cable, a Y-cable, two cables, oreven a "wishbone" cable (inverse Y), depending on the circumstances.Therefore, it will be apparent to those skilled in the art that otherchanges and modifications may be made to the invention as describedwithout departing from the spirit and scope of the invention as soclaimed.

We claim:
 1. An intelligent synchronous modem comprising:(a) at leastone connector having a plurality of pins, a first distinct set of pinscomprising a first port for a primary channel of communication with ahost computer and a second distinct set of pins comprising a second portfor a secondary channel of communication with a host computer, whereinthe primary communication channel is for communication of data mode dataand the secondary communication channel is for communication of commandmode data; (b) a microprocessor for receiving, recognizing, andexecuting commands of said host computer, wherein said command mode dataare in the form of asynchronous data received over said secondarycommunication channel; and (c) interface means for interfacing saidmicroprocessor with a telephone line, wherein said data mode datareceived by said microprocessor are sent to said interface means, andwherein said data mode data are in the form of synchronous data.
 2. Anintelligent synchronous modem according to claim 1, wherein:data modeand command mode data may be simultaneously communicated over saidprimary and secondary channels.
 3. An intelligent synchronous modemaccording to claim 2, further comprising:(d) scrambling means forscrambling said synchronous data into a proper format for transmittal toa second computer via said telephone line, and for unscrambling datacoming into said scrambling means from said second computer; and (e)data path logic circuitry, wherein said microprocessor is arranged tomodulate the synchronous data received for sending to said interfacemeans; said microprocessor outputs said modulated synchronous data in adigital parallel format; and said interface means is arranged to convertsaid parallel digital data received from said microprocessor into ananalog serial format. said microprocessor controls said logic circuitry,said data path logic circuitry is arranged to permit the conversion ofthe said modem into an intelligent asynchronous modem, and saidscrambling means is arranged to convert asynchronous data coming fromsaid host computer into clocked data for output to said microprocessor.4. An intelligent synchronous modem according to claim
 1. furthercomprising:(d) scrambling means for scrambling said synchronous datainto a proper format for transmittal to a second computer via saidtelephone line, and for unscrambling data coming into said scramblingmeans from said second computer.
 5. An intelligent synchronous modemaccording to claim 4, wherein:said microprocessor is arranged tomodulate the synchronous data received for sending to said interfacemeans.
 6. An intelligent synchronous modem according to claim 5,wherein:said microprocessor outputs said modulated synchronous data in adigital parallel format; and said interface means is arranged to convertsaid parallel digital data received from said microprocessor into ananalog serial format.
 7. An intelligent synchronous modem according toclaim 4, further comprising:(e) data path logic circuitry, wherein saidmicroprocessor controls said logic circuitry, said data path logiccircuitry is arranged to permit the conversion of the said modem into anintelligent asynchronous modem, and said scrambling means is arranged toconvert asynchronous data coming from said host computer into clockeddata for output to said microprocessor.
 8. A data communication system,comprising:(a) a host computer including asynchronous and synchronouscommunication ports, wherein said computer is arranged to send commandmode data through said asynchronous port, and data mode data throughsaid synchronous port; (b) an intelligent synchronous modem, includingfirst and second ports for primary and secondary channels forcommunication with said host computer, said first and second portscomprising first and second distinct sets of pins, wherein the primarycommunication channel is for communication of data mode data and thesecondary communication channel is for communication of command modedata, a microprocessor for receiving, recognizing, and executingcommands of said host computer, wherein said commands are in the form ofasynchronous command data received over said secondary communicationchannel, and interface means for interfacing said microprocessor with atelephone line, wherein said data mode data received by saidmicroprocessor are sent to said interface means, and wherein said datamode data are in the form of synchronous data;(c) at least one cable forconnecting said synchronous port of said host computer with said firstport of said modem, and for connecting said asynchronous port of saidhost computer with said second port of said modem; and (d) code/decodemeans for coding data of said host computer into a protocol forsynchronous communication, and for decoding synchronous communicationprotocol data received from a second computer into data understandableby said host computer.
 9. A data communication system according to claim8, wherein:data mode and command mode data may be simultaneouslycommunicated over said primary and secondary channels.
 10. A datacommunication system according to claim 9, wherein:said modem furtherincludes scrambling means for scrambling said synchronous data into aproper format for transmittal to a second computer via said telephoneline, and for unscrambling data coming into said scrambling means fromsaid second computer, and said microprocessor of said modem is arrangedto modulate the synchronous data received for sending to said interfacemeans, said microprocessor of said modem outputs said modulatedsynchronous data in a parallel digital format, and said interface meansof said modem is arranged to convert said parallel data received fromsaid microprocessor into an analog serial format.
 11. A datacommunication system according to claim 10, wherein:said modem furtherincludes data path logic circuitry, wherein,said microprocessor of saidmodem controls said logic circuitry, said data path logic circuitry isarranged to permit the conversion of said modem into an intelligentasynchronous modem, and said scrambling means is arranged to convertasynchronous data coming from said host computer into clocked data foroutput to said microprocessor.
 12. A data communication system accordingto claim 11, wherein:said host computer is arranged with two connectors,one of said connectors for said synchronous port of said host computer,and the other of said connectors for said asynchronous port of said hostcomputer; and said at least one cable comprises a cable which connectson one end to said connector of said modem, and is split on its otherend such that it is arranged to connect with said two connectors of saidhost computer.
 13. A data communication system according to claim 8,wherein:said modem further includes scrambling means for scrambling saidsynchronous data into a proper format for transmittal to a secondcomputer via said telephone line, and for unscrambling data coming intosaid scrambling means from said second computer.
 14. A datacommunication system according to claim 13, wherein:said microprocessorof said modem is arranged to modulate the synchronous data received forsending to said interface means.
 15. A data communication systemaccording to claim 14, wherein:said microprocessor of said modem outputssaid modulated synchronous data in a parallel digital format; and saidinterface means of said modem is arranged to convert said parallel datareceived from said microprocessor into an analog serial format.
 16. Adata communication system according to claim 13, wherein:said modemfurther includes data path logic circuitry, wherein said microprocessorof said modem controls said logic circuitry, said data path logiccircuitry is arranged to permit the conversion of said modem into anintelligent asynchronous modem, and said scrambling means is arranged toconvert asynchronous data coming from said host computer into clockeddata for output to said microprocessor.
 17. A data communication systemaccording to claim 8, wherein:said host computer is arranged with twoconnectors, one of said connectors for said synchronous port of saidhost computer, and the other of said connectors for said asynchronousport of said host computer; and said at least one cable comprises acable which connects on one end to said connector of said modem, and issplit on its other end such that it is arranged to connect with said twoconnectors of said host computer.